Electrodes so thin they are barely there could make brain treatments safer. Wires are sometimes implanted in the brain to treat epilepsy and Parkinsonâ€™s disease by stimulating malfunctioning nerve cells. They can also be used to record electrical signals inside the brain â€“ a useful tool for neuroscience.
But these electrodes are wide â€“ around 1.5 millimetres in diameter â€“ and kill brain cells and sometimes hit blood vessels when they are inserted. Because they are stiff, they cause inflammation in the brain and gradually become covered with immune cells that reduce their efficiency.
A better alternative would be thinner, softer electrodes such as carbon nanotubes, a thousandth of the diameter of regular wires. But how do you stick something soft into the brain? â€śItâ€™s like trying to stick a wet noodle into a bowl of Jello,â€ť says Jacob Robinson of the Rice University Department of Electrical and Computer Engineering.
Now Robinsonâ€™s team has found a way to temporarily make a nanotube behave more like a stiff knitting needle than a noodle. They have built a device with a tiny channel of flowing water to stiffen the wire. As the nanotube is pushed into the brain, the surrounding tissue stops it from crumpling.
The device was used to insert electrodes that record brain activity in mice, seemingly without causing any damage, the team told an IEEE workshop in San Diego in November. The nanotubes should enable researchers to study brain activity over much longer periods.
This article appeared in the January 7 print issue of New Scientist.